Hydrocarbon oxidation is an established process in the chemical and petroleum refining industries, and many oxidized hydrocarbons are known to have commercial value. For example, organic carbonates, such as dimethyl carbonate (DMC), are known to be valuable as intermediates in many chemical processes and as synthetic lubricants, solvents, plasticizers, and monomers for organic glass and various polymers, such as polycarbonate.
A common method for producing dimethyl carbonate is the oxidative carbonylation of methanol. A disadvantage associated with this method is the corrosive nature of copper and bromine catalysts used. Another disadvantage is the incomplete conversion of the starting alcohol, which can lead to the formation of methanol/DMC azeotropes and subsequent difficulties in downstream processing.
Several alternative processes have been proposed, such as the formation of DMC from methanol and supercritical CO2. However, the reaction conditions are harsh and a large amount of molecular sieve is required to obtain a significant conversion.
Of particular importance in all oxidation processes is the degree of conversion of the starting materials and the selectivity of conversion into the desired products. Thus, there is a need for efficient processes for the oxidation of hydrocarbons, and in particular for the oxidation of dimethoxy methane (DMM) to dimethyl carbonate (DMC), which processes are highly selective and/or have high degrees of conversion.
Background references include U.S. Pat. No. 5,536,864 to Paret, et al.; U.S. Pat. No. 5,550,278 to Rechner, et al.; U.S. Pat. No. 5,498,743 to Shih, et al.; U.S. Pat. No. 6,008,399 to Chang, et al.; Japanese Patent No. 20000119225 to Mitsubishi Gas Chem Co; U.S. Pat. No. 6,555,715 to Kocal, et al.; U.S. Patent Application Publication 2003/0083527; Japanese Patent Application Publication No. 2002-282698; U.S. Pat. No. 5,958,821 to Ishii, et al.; and PCT Publications WO2004/046076 and WO2004/045767; the entire disclosures of which are hereby incorporated herein by reference.